It is known that gear units having oil lubrication are practicable, the oil, that is, fluid, collecting in the lower part of the interior of the gear unit when the gear unit is not in operation, that is, when the gears are at rest, where it forms the oil sump that has an oil level corresponding to the filling level when filling in the oil. When operating the gear unit, in particular at the nominal speed of the input shaft and/or output shaft, the toothed parts of the gear unit spray and centrifuge the oil around. In particular, the mutually engaged toothings also spray out oil.